either in space or time. And we have different different symbols
to represent the two, but they're they're analogous to each other, okay.
And so, I can do the same thing with with in the time domain I can represent that
same [UNKNOWN] response characteristic, and this just happens to be one period of
oscillation. So, the amount of time it takes here is
one period of oscillation for this particular wave, all right, to propagate.
Now, when we move to sound wave propagation in air.
we can easily relate to wavelength to the frequency.
And that's done through the speed of sound.
And so, in air in particular. And so, before we get into those details
we need to define a few basics. So, we need to define our, you know,
we'll do it at room temperature that's what we're going to be working at,
especially around the concept of speaker design and typical acoustics in the
musical range. but speed of sound in air is roughly 340
meters per second 343 at 20 degrees c. And then the density of air, which is
important as well for some of the calculations we make, is 1.21 kilograms
per meter cubed. And you notice that I'm working in the
metric units here. Alright.
So, the relationship between wavelength and frequency of sound and air is fairly
simple. And it's expressed here, lambda, the
wavelength of the frequency. the wavelength, special wavelength, is
related to the speed of sound in air. Remember that's, that's in meters per
second. And frequency is m1 over seconds, so, you
know, if you look at the units on this, you have meters per second divided by 1
over second, which gives you units of meters, all right?
And that makes sense, because the wavelength is going to be represented in
a measure of meters. so let's talk a little bit about the
relationship between, our audible range, and then of course the the wavelength of
sound in the audible range. So, humans actually hear sound in
wavelengths that range from about 20 hertz at the low frequency to 20
kilohertz at high frequency. And you know the older you get actually
you get you, your, your response at higher frequencies decreases.
we know that but, but It's but at birth basically you have a, a range of about 20
hertz to about 20 kilohertz, and it varies from person to person depending on
auditory capabilities. So, you've just computed the wavelength
of sound at 20 hertz. what is the wave length of sound at 20
kilohertz? It's pretty simple all you have to do is
divide that by a thousand. and if you do that you get a wave length
of 1.7 centimeters. So, if our audible range is from 20 hertz
to 20 kilohertz, that's the frequency range over which we hear it corresponds
to wavelengths that range from 17 meters to 1.7 centimeters.
So, the wavelength the sound at 20 hertz is 17 meters long.
Now that's, that's, that's a large wavelength.
If you think about the, look around your surroundings at your room most of you
probably aren't in a room at this point in time that has a dimension of 17 meters
in any given dimension. So, this a really long wavelength,
particularly compared to the size of your head and the distance between your ears.
at high frequency, though at 20 kilohertz for example, wavelengths only 1.7
centimeters long, so it's very short. So, this is important because it's, it's
important in particular in relation to how we actually localize sound.